3D surface extraction from a 3D cube

Hi there,

I would like to extract 3D surfaces from a 3D cube.

In order to clarify my pupose, let’s take a simpler case: I have 3 2D grids data where values represent z value.

This is what I want and obtain:

OK, that’s for the simpler case (it’s just 3 VTK UnstructuredGrid with 3D points where z values are the data values).

Now, what I would like to do is to get the same display, but with only one 3D grid data (where 3 2D grids data are stacked, in fact).

I think about something like this:

3D grid data
→ extraction of the first slice → elevation of the slice vs z values
→ extraction of the second slice → elevation of the slice vs z values
→ extraction of the third slice → elevation of the slice vs z values

So my question is: what kind of filters can I use to do this ?

Obviously, I could do the same as in the simpler case, ie extract 3 VTK UnstructuredGrid from the 3D cube, but in real case I have a lot of 3D surfaces, so it would be cumbersome to do it like this.

Thanks in advance.


Answering questions like this is always easier if you can post some example data to give us a better idea if what we are looking at.

It looks like you have 3 separated sheets. As long as you are sure they are separated and the connectivity within a sheet is correct, you can use the Connectivity filter to identify the connected sheets. This filter will create a new point field named RegionId that has a unique identifier for each connected region. In the example you posted, it should have RegionIds 0, 1, and 2 with each assigned to one of the sheets.

After you run the Connectivity filter, just use Threshold to pull out the sheet you want.


Thanks for the answer.

Please see the attached vtkImageData file:
horizons.vti (740.8 KB)
It’s a stack of 3 201*301 cells 2D grids.

Values in each of these 3 2D grids represent a z value.
And rather than display these 3 2D grids as horizontal planes, I would like to display them as 3 3D-surfaces “elevated” with their z values.

I’m not sure I get the point of what you suggest above, btw.
There is no connectivity info in the VTK file.